1. Field of the Invention
The present invention relates to orthopedics, and more particularly to implants and procedures for orthopedic applications.
2. Description of Related Art
A variety of devices and procedures are known in the art for implanting devices in orthopedic applications, such as intervertebral implants, acetabular cups, and glenoid fossa prostheses. As one example, intervertebral spacers are usually made of PEEK, bone, or titanium. They are used to restore disc height and create a rigid anterior spinal column which assists in fusion rates. Intervertebral spacers have been made in a variety of shapes but routinely simulate the vertebral body structure in an effort to rest on the cortical rim which consists of denser bone than the cancellous bone found in the center of the endplates. Spacers resting primarily on cancellous bone would subside because cancellous bone is less dense, and the subsidence would reduce the effect of expansion of intervertebral height and neuroforaminal space thereby leading to nerve impingement. Spacers are often made with ridges on the top and bottom surfaces to resist displacement. Additionally, screws have been used to supplement the fixation and rigidity of the construct.
When utilizing an intervertebral spacer as a lumbar implant, for example, the surgeon typically applies the implant through an abdominal anterior or lateral incision via a retro- or transperitoneal approach. Given the significant distance from the abdominal wall to the anterior spine due to the girth of the patient, which can be even greater for larger patients, application of the interbody spacers and fixation can pose a difficult challenge. The implants are routinely placed into the disc space in a linear fashion using implements at the end of long, straight instruments.
The application of additional fixation with current screw technology often proves extremely difficult given the limited angles which can be obtained for long instruments through a small incision often as far as 8-12 inches from the spine. Many traditional spacers have oblique slots for screws to pass in through the side of the spacers that face the surgeon during implantation, and out the superior or inferior side of the spacer to allow for direct fixation from the spacer to the adjacent vertebra. These oblique slots are usually applied at angles of 30° to 45° relative to the top and bottom surfaces of the spacers. Due to geometrical limitations of typical incisions described above, the oblique slots require the use of screw drivers, drills, and/or awls employing universal joints near their distal ends. These instruments can be dangerous to use because of the requirement for the surgeon to apply a translational force to the head of the instrument to engage the implant obliquely, which can lead to slipping. Slipping with such an instrument can cause damage to the adjacent vascular and visceral structures which are immediately adjacent to the spine and are often retracted at the time of application of the implants.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for methods and devices that allow for improved application of orthopedic implants. There also remains a need in the art for such implants that are easy to make and use. The present invention provides a solution for these problems.